1. Field of the Invention
The present invention is generally related to a marine exhaust elbow and, more particularly, to an.exhaust elbow that has a tubular insert contained within its structure to enhance its capability of draining.
2. Description of the Prior Art
Many different types of exhaust elbows for use in marine propulsion systems are well known to those skilled in the art. Typically, an exhaust elbow is used in conjunction with an exhaust manifold structure to direct the flow of exhaust gases and cooling water toward the aft portion of a marine vessel for subsequent discharge overboard.
U.S. Pat. No. 6,290,558, which issued to Erickson on Sep. 18, 2001, discloses an exhaust elbow with a water trap for a marine propulsion system. The exhaust elbow for a marine propulsion exhaust system is provided with a water trap section that defines a water collection cavity. Within the water trap section, a barrier extends downward into the water collection cavity to define first and second exhaust passages. When water begins to collect in the water collection cavity, the cross sectional area of the exhaust passage is reduced and the velocity of exhaust gases passing through the exhaust passage is increased. The water collection cavity is shaped to be easily cleared when exhaust gas pressure increases as the engine speed increases.
U.S. Pat. No. 6,022,254, which issued to Neisen on Feb. 8, 2000, discloses an exhaust system for an inboard/outboard marine propulsion system. The exhaust system includes intermediate exhaust pipes which are physically separate components from the water separator. A sealed latching mechanism connects an outlet portion of the intermediate exhaust pipes to an inlet portion of the water separator. The sealed latching mechanism is secure yet flexible and allows the orientation of the intermediate exhaust pipe to be adjusted relative to the water separator, thus allowing the exhaust system to be installed and serviced without dismounting or loosening the engine. The intermediate exhaust pipes also have a flared inlet part to facilitate alignment of the intermediate exhaust pipe at the exhaust elbow.
U.S. Pat. No. 5,910,095, which issued to Strasser et al on Jun. 8, 1999, describes a fiber reinforced ceramic matrix composite marine engine riser elbow. A corrosion-resistant, thermally insulative riser elbow for a marine engine is described. The riser elbow has an exhaust gas conduit made of fiber reinforced ceramic matrix composite (FRCMC) material formed from a polymer derived ceramic resin in its ceramic state and fibers. Employing a FRCMC material results in a low-cost, light-weight, corrosion-resistant exhaust gas conduit not available with existing riser elbows. In addition, a FRCMC exhaust gas conduit is thermally insulated and so more of the heat of the exhaust is retained rather than being transferred to the conduit. This allows the cooling requirements of the riser elbow to be lowered, while still maintaining a touch temperature below prescribed levels.
U.S. Pat. No. 5,109,668, which issued to Lindstedt on May 5, 1992, discloses a marine exhaust manifold and elbow structure. The assembly includes a manifold portion, an elbow portion, a water jacket portion, and exhaust runner walls, providing a smooth continuous transition of exhaust gas flow from intake exhaust passages in the manifold portion to transfer exhaust passages in the elbow portion around a bend to a discharge exhaust passage, minimizing turbulent flow of exhaust through the manifold portion and elbow portion. Each transfer exhaust passage has its own water supply inlet at the upstream end of the respective intake exhaust passage. An upper vent includes a steam outlet opening in the water jacket at the high point of the elbow portion, and a steam exhaust channel extending along the top exterior of the water jacket portion in a raised bead above and parallel to an upper water flow passage and directing steam to the end of the discharge end passage to mix with water and exhaust thereat. Wall supports assist in directing cooling water up through the water jacket to the top of the elbow bend and also prevent wall collapse during lost foam stainless steel casting.
U.S. Pat. No. 4,991,546 which issued to Yoshimura on Feb 12, 1991, describes a cooling device for a boat engine. A number of embodiments of cooling systems for internal combustion engine powering marine watercraft are described, wherein the engine cooling jacket delivers its coolant to an exhaust manifold cooling jacket adjacent the inlet end of the exhaust manifold and wherein coolant is delivered from the exhaust manifold cooling jacket to a further cooling jacket around the inlet portion of exhaust elbow. In one embodiment, a closed cooling system is provided for the engine cooling jacket, exhaust manifold cooling jacket and the elbow cooling jacket. In another embodiment, the system discharges coolant back to the body of water in which the watercraft is operating through a further cooling jacket of the exhaust elbow that communicates with its discharge end.
U.S. Pat. No. 4,977,741, which issued to Lulloff et al on Dec. 18, 1990, discloses a combination exhaust manifold and exhaust elbow for a marine propulsion system. A combination exhaust manifold and exhaust elbow for an internal combustion engine includes an exhaust cavity for receiving exhaust from the engine, an exhaust passage leading from the exhaust cavity, and an exhaust discharge outlet. A first water jacket is provided around the exhaust cavity and a second water jacket is provided around the exhaust discharge passage. A dam is provided between the first and second water jackets, having a passage therein for allowing water communication between the first and second water jackets. A warm water inlet is provided in the first water jacket around the exhaust cavity for receiving cooling water which has been warmed by the engine, and which flow is controlled by a temperature sensitive thermostat. A cooled water inlet is provided adjacent the discharge exhaust passage. The cold water inlet is disposed either upstream or downstream of the dam adjacent the exhaust passage and allows cold bypass water to be discharged without the necessity of the cold water flowing through the entire assembly so as to prevent moisture from condensing out of the exhaust in the exhaust cavity.
U.S. Pat. No. 4,866,934, which issued to Lindstedt on Sep. 19, 1989, disclosed a marine drive exhaust system with shaped O-ring seals. The marine drive exhaust system is provided with resilient, shaped rubber O-ring seals between facing surfaces of the exhaust manifold and exhaust elbow and the facing surfaces of the exhaust elbow and the exhaust pipe. Each of the shaped O-ring seals has an inner peripheral rib extending peripherally around the exhaust passage and generally conforming to the shape thereof and being spaced laterally between the exhaust passage and the peripheral water passages. Each of the shaped O-ring seals has an outer peripheral rib extending peripherally around the water passages and spaced laterally outward of the inner rib by a gap through which the water passages extend.
U.S. Pat. No. 4,845,945, which issued to Widmer et al on Jul. 11, 1989, discloses an exhaust elbow trough. A water jacketed exhaust elbow for a marine propulsion system includes an intake exhaust passage communicating with a discharge exhaust passage, a water jacket around the exhaust passages, and a trough member extending longitudinally along a water channel along the exterior of the discharge exhaust passage to guide water therealong to mix with exhaust at the end of the discharge exhaust passage. The trough member extends beyond the end tip of the discharge exhaust passage and has a sharp edge providing a clean parting surface for the cooling water and preventing ingestion of water back into the discharge exhaust passage.
U.S. Pat. No. 4,573,318, which issued to Entringer et al on Mar. 4, 1986, discloses an exhaust elbow for a marine propulsion system. The marine propulsion system is provided with an exhaust elbow having an intake exhaust passage extending upwardly from the engine and communicating through a bend with a discharge exhaust passage, a water jacket having pockets around the exhaust no passage for cooling the latter. A central channel extends longitudinally along the exterior of the exhaust passages to guide water therealong to the end of the discharge exhaust passage to mix with exhaust thereat. The central channel has a pair of side walls extending longitudinally and laterally tapered away from each other at the outer end of the discharge exhaust passage to create an outward draw as from the central channel to minimize break-up of longitudinally outward water flow and maintain the end tip of the discharge exhaust passage dry and prevent water ingestion and creeping back into the discharge exhaust passage due to pulsations of the engine. Dam and port structure is also provided enabling faster heating of the exhaust passage and in turn minimizing condensation within the elbow which may otherwise ingest back into the engine.
U.S. Pat. No. 5,174,252, which issued to Binversie et al on Dec. 29, 1992, describes an exhaust manifold expansion slot for an internal combustion motor. A multiple cylinder internal combustion cylinder block having a cast exhaust manifold means integrally cast with the block is disclosed. The manifold means includes manifold port portions that communicate with the cylinder bores, and an expansion slot is provided in the manifold port portions adjacent the cylindrical bores to relieve stress which tends to distort the cylindrical bores of the block.
U.S. Pat. No. 5,018,568, which issued to VanRens on May 28, 1991, describes a lost form engine block pattern. The engine block pattern for an engine block includes a cylinder and an axially extending transfer passage defined by spaced side walls and an inner wall which is outwardly convex. The pattern further includes a first pattern piece including a wall defining a portion of a cylindrical bore having an axis, and a passage recess extending in the direction of the axis of the cylindrical bore and communicating with the cylindrical bore, which so passage recess is defined by opposing walls extending axially with respect to the cylindrical bore and forming the spaced side walls of the transfer passage, a second pattern piece located in the passage recess, having a first arcuate wall forming a continuation of the cylinder bore portion of the first pattern piece, having a second arcuate wall forming the inner wall of the transfer passage and being outwardly convex and additional recesses and portions on the first and second pattern pieces for locating the pattern pieces relative to each other and preventing relative movement therebetween except in the direction opposite the direction of assembly of the pattern pieces.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
Many different types of exhaust elbows are known to those skilled in the art. In addition, the process of lost foam casting is well known to those skilled in the art. Furthermore, lost form casting techniques which incorporate inserts in the lost foam pattern prior to casting the primary metal structure are known.
Since many exhaust elbows are made of cast iron material, it would be significantly beneficial if a means could be provided to prevent the decrease in cross sectional area of drain openings which are intended to allow cooling water to drain from engine components when the internal combustion engine is not in operation. This decrease in drain area can be caused by corrosion.
An exhaust gas conducting system for a marine propulsion system made in accordance with the present invention comprises an exhaust conducting structure made of a first material and an exhaust gas cavity formed within the exhaust conducting structure. The exhaust, gas cavity has an exhaust inlet opening and an exhaust outlet opening. A water cavity is formed within the exhaust conducting structure and is disposed in thermal communication with the exhaust gas cavity. The water cavity has a water inlet opening and a water outlet opening. A tube is disposed within the water outlet opening and in fluid communication with the water cavity. The tube is made of a second material. The first material is different than the second material.
In a particularly preferred embodiment of the present invention, the first material is cast iron and the second material is a stainless steel alloy. In certain embodiments of the present invention, a supplemental tube is also disposed within the water outlet opening and in fluid communication with the water cavity. The supplemental tube is made of the second material.
In a preferred embodiment of the present invention, the exhaust conducting structure is an exhaust elbow and the tube is cast into the exhaust conducting structure, as an insert, during the lost foam casting process. The tube is cast into the exhaust conducting structure at a time when the first material is molten in a preferred embodiment of the present invention.
The water cavity surrounds the exhaust gas cavity within at least a portion of the exhaust conducting structure in one embodiment. The water cavity can conduct either salt water or fresh water in thermal communication with the exhaust gas cavity and the second material can be UNS S31600 stainless steel.